We would like to create an "interaction" matrix.

I would manually enter data in a column. I would want this data
automatically created in column heads.
A B C D
1
2 =A3 =A4 =A5
3Item#1
4Item#2
4Item#3

Since if expect a large number of items, I want to "fill by example" the
rest of row 2. I just can't find out how to do this.

Thanks in advance.